CircPCNX1-mediated Regulation of Pulmonary Artery Smooth Muscle Cell Proliferation and Migration in Rat Model of High Pulmonary Blood Flow-induced Pulmonary Arterial Hypertension

In this study, we investigate the regulatory role of the circular RNA circPCNX1 in modulating the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) under high pulmonary blood flow-induced pulmonary arterial hypertension (PAH). A rat model of PAH was established via abdominal aorta-inferior vena cava shunting. The circular structure and subcellular localization of circPCNX1 were confirmed through Sanger sequencing, RNase R digestion assays, and fluorescence in situ hybridization. The expression level of circPCNX1 in PASMCs was verified by qRT-PCR. The effects of circPCNX1 on the proliferation and migration of PASMCs were explored through lentivirus transfection, cell-proliferation assays, and cell-scratch assays. The potential regulatory mechanism of circPCNX1 in the proliferation and migration of PASMCs was explored through online database prediction of combined microRNA (miRNA), RNA antisense purification, luciferase reporter assay, lentivirus transfection and gene-function enrichment test. We confirmed the circular structure of circPCNX1 and its cytoplasmic localization. circPCNX1 expression was downregulated in PASMCs of rats in high pulmonary blood flow-induced PAH. Functional experiments confirmed that overexpressed circPCNX1 inhibited PASMC proliferation and migration. RNA antisense purification and luciferase reporter assays demonstrated that circPCNX1 directly binds to miR-22-5p. Gene-function enrichment analysis revealed that the downstream target genes of miR-22-5p are predominantly enriched in the cGMP-PKG signaling pathway. Therefore, circPCNX1 regulates the proliferation and migration of PASMCs through direct interaction with miR-22-5p, and thereby modulates the cGMP-PKG signaling pathway.